The need to artificially introduce food into the gastrointestinal tracts of individuals who can not eat, or will not eat, has been well known throughout and even prior to this century. Before the mid-1970's, feeding was done nasogastrically with red rubber or polyvinylchloride feeding tubes. The use of enteral feeding by means of nasogastric tubes expanded dramatically in the late 1970's with the introduction of tubes constructed of either silicone rubber or polyurethane. Being constructed of stronger materials, these tubes incorporated thinner walls, and were therefore smaller in outside diameter. These smaller tubes were easier to insert and more comfortable for the patient, and their introduction resulted in a very rapid growth of enteral nutrition via the nasogastric route, and increased interest in enteral nutrition in general.
By the 1980's problems with nasogastric feeding were recognized by clinicians and the advantages of direct gastrostomy access into the stomach through the abdominal wall had been described by Vazquez in U.S. Pat. No. 4,356,824, and by Moss in U.S. Pat. No. 4,543,085. Refinements in securing gastrostomy tubes in the patient were described by Parks in U.S. Pat. No. 4,666,433 and in U.S. Pat. No. 4,685,901.
The 1980's also saw the refinement of methods for forming the gastrostomy stoma. Prior to the 1980's, the stoma or gastrostomy was formed surgically by the Stamm procedure, which required a surgical laporatoratomy to insert the tube, usually a latex urologic Foley retention catheter. A new method, called a "PEG", or Percutaneous Endoscopic Gastrostomy, eliminated the need for a surgical gastrostomy to place the gastrostomy tube and dramatically expanded the interest in the use of direct gastrostomy tubes. The advantages of PEGs and the PEG technique were described by Quinn et al in U.S. Pat. No. 4,795,430. The word "PEG" is used herein to identify both the tube and the procedure.
Gastrostomy tubes can generally be organized into three main groups, the third of which includes two subgroups:
1. SPECIALTY TUBES placed at the time of gastric surgery by the Stamm technique. The Moss and Vazquez patent tubes are examples of this type. PA1 2. PEG tubes which are used to form the initial stoma or gastrostomy. PA1 3. REPLACEMENT TUBES which are used to replace the PEG tube after a period of time because the PEG has worn out with use, or because a device which is more specific to the patient's need is required. These tubes are inserted into the original stoma created by either the PEG or the Stamm technique. PA1 1. A tube to carry the enteral feeding formula into the stomach and or the intestine. PA1 2. An outflow port in the distal end of the tube. The port or ports may be incorporated in the end or the side wall of the tube. They may also be incorporated in a separate, molded bolus fastened to the distal end of the tube. PA1 3. An administration set connector attached to the proximal end of the tube, which is outside of the patient. PA1 4. A distal end retention device to hold the tube in the stomach, e.g., an inflatable balloon or a molded retention shape which can be deformed with a stylet for insertion and removal. PA1 5. An external bolster to secure the tube at the point where it exits the skin. This bolster maintains the proper distance between the external bolster and the internal retention device, a distance corresponding to the combined thickness of the individual patient's skin, abdominal wall and stomach wall at the site of the gastrostomy. PA1 6. An anti-reflux valve to prevent leakage of gastric acids from the patient when the administration set is being changed or when violent coughing causes excessive back pressure. PA1 7. A measurement system to measure the patient's abdominal wall thickness so that the tube length between the retention device and the external bolster can be adjusted to match this thickness. PA1 Difficulty of insertion and removal. PA1 Difficulty of obtaining accurate measurement of required tube depth. PA1 Lack of durability of internal retention devices. PA1 Incompatibility of replacement gastrostomy tubes with PEGs. PA1 Valve failure. PA1 Infection of the stoma. PA1 Difficulty in cleaning of the stoma. PA1 The need for many tube sizes. PA1 Inability to secure the tube adequately with an external bolster. PA1 The need for special administration sets. PA1 1. THE TUBE. Silicone and polyurethane are the materials of choice for these tubes. Silicone is softer and more compliant than polyurethane. Silicone has a lower modulus of elasticity than urethane. Softness is desirable in medical catheters. However, softness also increases the ability to kink and collapse, which are undesirable characteristics. These problems have heretofore been addressed by making tube walls thicker in silicone tubes or by constructing the tubes from the stronger, but less flexible, polyurethane. The designer has had to make a choice between a smaller, but less flexible, urethane tube and a larger, softer silicone tube. PA1 2. OUT FLOW PORT IN DISTAL END OF TUBE. The problems with conventional nasogastric feeding tube outlet ports as to insertion, flow and clogging are described by Andersen et al. in U.S. Pat. No. 4,594,074. These problems are also common to gastrostomy tubes. PA1 3. ADMINISTRATION SET CONNECTOR. Existing low profile tubes have administration set connectors which exit perpendicular to the patient's skin. This configuration is described in Quinn et al. U.S. Pat. No. 5,125,897. To prevent the administration set from kinking and twisting, special sets with right angle connectors must be used so that the administration set tubing can lie comfortably on the patient's abdomen. PA1 4. DISTAL END RETENTION DEVICE TO HOLD THE TUBE IN THE STOMACH or bladder. Tubes with inflatable silicone retention balloons are easy to insert because the uninflated balloons are formed completely flat against the tube wall. However, they are unreliable because the silicone balloon walls which are stretched thin tend to break easily. In addition they must incorporate a second inflation lumen in the tube to access the balloon. This feature makes the tube larger and also requires the incorporation of a balloon inflation valve which adds cost and bulk to the product. PA1 5. EXTERNAL BOLSTER. Existing technology for bolsters is well known, as the aforementioned prior art illustrates. Some bolsters secure the tube, but do not bend it at a right angle to position it out of the way, next to the skin. Others secure and bend it at a right angle, but are rigid parts which can be uncomfortable for the patient. None of these rigid bolsters achieve full, right-angle bending of the tube due to the stiffness of the tubing. PA1 6. ANTI-REFLUX VALVE. Existing valves include flapper valves which clog and malfunction. Furthermore, it is often necessary to open the valve to decompress the stomach or bladder, so location of the valve is also important. Some gastrostomy valves are positioned so that special decompression sets are required to activate them if feeding is not taking place. PA1 7. TUBE MEASUREMENT AND SIZING. PEGs and simple gastrostomy tubes, for example, are sized to the patient after they are inserted. The position of the external bolster is approximated by simultaneously tugging on the internal retention member and then pushing the external member down on the skin. This is an imprecise method. Low profile replacement tubes have separate stoma depth measuring tools which are pre-inserted into the stoma. The clinician then selects a tube which corresponds to this measurement from a large selection of tube lengths. These tubes can not be adjusted for a change in patient size.
a. LOW PROFILE REPLACEMENT TUBES which are preferred for active patients who wish to conceal the tube's outer fitments during periods when they are not receiving feeding formula. The background for this type of replacement tube is described by Quinn et al in U.S. Pat. No. 5,125,897. PA2 b. SIMPLE REPLACEMENT tubes which are less complicated and less expensive are used for patients who are not active and have no need to hide their device. These devices are direct modifications of the original urologic Foley catheters used in early gastrostomies. They are described by Parks in U.S. Pat. No. 4,666,433.
With some exceptions within individual designs, gastrostomy tubes or tube assemblies of the aforedescribed types each incorporate the following seven features or components:
Just as gastrostomy tubes or tube assemblies are used for enteral feeding, so suprapubic catheter tubes or tube assemblies are used to administer drugs to, or drain urine from, the bladder. Such tubes or tube assemblies comprise the same seven features or components referred to above in the context of gastronomy tubes or tube assemblies. However, they access the bladder through a stoma formed in the abdominal wall above the bladder or pubic area.